The present invention relates to a universal cassette capable of housing plural recording papers having different sizes and a device to display the size of the recording papers housed in aforesaid universal cassette integral in an image forming apparatus.
As a means for feeding a recording paper into an image forming section inside an image forming apparatus, various paper feeding cassettes capable of feeding papers stably are frequently used. However, in order to attain a simpler structure and lower price, there are several paper feeding cassettes which can only house limited kinds of sizes. Namely, both sides guide members which maintain recording papers at a prescribed position in a paper feeding cassette and a trailing end stopping member which stops trailing end of recording papers to the paper feeding direction are fixed in a paper feeding cassette. Therefore, recording papers having several prescribed sizes can be housed. If the above-mentioned type paper feeding cassettes are used, in order to use recording papers having several other kinds of sizes, it is necessary to house many kinds of paper feeding cassettes which are used exclusively for a respective recording paper size in an image forming apparatus, causing the entire apparatus to become rather large.
Accordingly, a universal cassette capable of housing plural sizes of recording papers has come to be used. With regard to the structure of aforesaid universal cassette, guide members at the both sides of the recording papers and at the trailing end stopping member which stops trailing end are provided slidably for various sizes of recording papers. After aforesaid members are slid to the prescribed positions corresponding to each size, they are fixed for maintaining recording papers. In this situation, due to synchronous movement of the above-mentioned cam member and the sliding movement of the trailing end stopping member which touches a cam member formed on recording papers size detection member, plural units of the above-mentioned recording papers size detection members operate.
In a universal cassette constituted as above, when replacing recording papers having different sizes each other, the trailing end stopping member which stops trailing end of recording papers is slid in accordance with the size of recording papers. When the size of the recording paper is changed from a smaller to larger, or when the position of the paper is changed from a horizontal one to a vertical one, the length of sliding of the above-mentioned trailing end stopping member becomes longer. When conducting aforesaid sliding operation, the above-mentioned trailing end stopping member touches plural cam members. Accordingly, movement operation of the above-mentioned trailing end stopping member cannot be conducted smoothly. In addition, more or less skill was necessary for stopping the above-mentioned trailing end stopping member at the correct position while it touches cam members. Therefore, there were cases in which recording papers was housed in the universal cassette without stopping the above-mentioned trailing end stopping member at a precise position. In such occasions, recording papers could not be fed stably, causing jamming.
Further, in order to slide the trailing end stopping member, parts such as rails, guides, stoppers, sliding members and handles are necessary. Therefore, structure of the apparatus becomes complicated. Similarly, the structure of the recording paper size detection member becomes complicated.